Medical device with partially transparent housing

ABSTRACT

A device is provided having a housing with a housing wall consisting of a non-transparent plastic with an outer surface and an inner surface; and an operating mode display unit with at least one light-emitting element which is/are located inside the housing, underneath the inner surface of the housing wall. The housing wall has at least one recess in the area of the light-emitting element and the light intensity of the at least one light-emitting element is adjusted in such a way that in its light-emitting mode, said at least one light-emitting element is only optically perceptible in a localizable manner through the housing wall in this area.

[0001] The invention relates to a device, comprising a housing and adisplay unit, which can be optically perceived through the housing wall.The device is preferably a medical device.

[0002] There are known illuminated switches with a housing, as describedin U.S. Pat. No. 4,778,967. An illuminated operating element, such as abutton, which has a receptacle made of transparent material and acts asa light guide is known from DE 37 15 528 C2.

[0003] The prior art also discloses devices comprising a housing and adisplay unit with light-emitting elements, the light-emitting elementsusually being optically perceptible through a window which is fitted ina clearance in the housing wall.

[0004] Such devices are customary in particular in the medical sector,in cases where it is desired to make information optically perceptible.

[0005] The disadvantage of such devices is that, owing to the windowmade in the housing wall, there are crevices, fissures or recesses inthe housing wall, which easily become soiled but can only be cleaned, inparticular disinfected, with great difficulty.

[0006] Added to this is the fact that, owing to the considerable numberof parts, these devices are relatively complicated to produce andconsequently lead to relatively high costs in production.

[0007] Consequently, it is an object of the present invention to providea device which avoids these problems.

[0008] It can be regarded as a further object to provide a device whichpermits the detection of items in the vicinity of the device.

[0009] This object is achieved by a device such as that described in theclaims.

[0010] The terms “comprise” or “include” introduce a list of featureswhich is not considered to be exhaustive. The fact that the word “a” isused in the claims before stating a feature does not exclude thepossibility that the features stated may be present as a plurality, inthe sense of “at least one”.

[0011] The invention has the following advantages:

[0012] The device according to the invention can be cleaned easily andeffectively, since the device does not have to have clearances in thearea of the display unit for incorporating a window in order for thelight-emitting elements to be optically perceptible.

[0013] The largely uninterrupted surface of the housing of the devicehas the effect of making production easier, since no cutouts need bemade in the housing.

[0014] For the purposes of the present invention, a housing isunderstood as meaning any external enclosure of a device which has anylight-emitting display unit. The housing may be produced from just onepart and consist of one and the same material, but may also be made upof different elements, which for their part contain different materials.

[0015] The primary purpose of the housing is to protect the componentslocated in the housing from external influences, in particularmechanical influences. In this respect, the housing is preferablyproduced from a material that is resistant to rupture. The housing ispreferably also largely encapsulated and, apart from necessary aperturesin the form of ventilation slits or apertures for cables, has noopenings.

[0016] The housing wall is preferably made from one and the samematerial. The housing wall is predominantly of the same thickness.Housing wall thicknesses in the range from 1 to 5 mm, preferably from 2to 3 mm, are customary.

[0017] The term non-transparent comprises materials which, when heldagainst a dark surface, under normal lighting intensity do not allowthis surface to be optically perceived, preferably by the human eye oran optical sensor, for example a photocell, through the material.Consequently, translucent materials such as acrylic glass are notincluded.

[0018] A display unit is to be understood as meaning electricallyoperable component parts of a device which optically displaysinformation on some operating state or other of the device. Suchinformation may be, for example, the charging state of the batteries ofa battery-operated device, information on the light intensity given offby an illuminating device, the on state, the operating mode or errormessages.

[0019] The term light-emitting elements comprises all elements which,when operated with electric current, can emit light, such asincandescent lamps, light-emitting diodes (LEDs), 7-segment displaysand/or laser diodes.

[0020] The radiation transmitted by the light-emitting elements lies inthe range from 400 to 1300 nm. For use as a display, wavelengths in therange from 400 to 700 nm have proven successful; for the application fordetecting items, wavelengths in the range from 600 to 1300 nm haveproven successful.

[0021] The radiant power lies, for example, in the range from 0.1 to 30mW, preferably in the range from 1 to 10 mW.

[0022] The device according to the invention has at least onelight-emitting element, preferably two, three or more light-emittingelements.

[0023] For the purposes of the invention, optically perceptible meansthat, under customary artificial or natural lighting, it can beperceived, preferably with the human eye, whether or not alight-emitting element is radiating light. Depending on the desiredembodiment, however, radiation sensors such as photocells, photodiodesor phototransistors may also be used for the optical perception.

[0024] The presence of a light-emitting element is not perceptible fromthe outside in the non-emitting state, whereas in the emitting state theemission of the light-emitting element is optically perceptible from theoutside through the housing wall in an area which can largely be sharplydelimited. This must be distinguished from a diffuse emission, whichcannot be clearly assigned to an area which can be delimited, as isknown for example in the case of internally illuminated switches.

[0025] Of course, the device also has a switching unit, by means ofwhich the device can, for example, be put into the operating state. Theswitching unit may be formed as a power switch, a changeover switchand/or an on switch. The switching unit is usually in the form of apushbutton, a toggle switch or a rotary switch. The housing usually hasno clearance at this point.

[0026] The optical perceptibility of the light-emitting elements isachieved through the housing wall by reducing the wall thickness of thehousing wall, preferably on the inner side of the housing. This leads toa reduction in the layer thickness of the housing wall (recess) andconsequently to an increase in the transparency at this point.

[0027] For the purposes of the invention, a recess exists when the layerthickness of the housing wall is less at this point in comparison withthe customary layer thickness of the housing wall. A reduction by atleast 50%, preferably in the range from 60 to 90%, has proven to beadvantageous. In this range, the housing wall is, for example, onlyabout 0.2 to 0.8 mm, preferably 0.3 to 0.6 mm, thick.

[0028] Consequently, the term recess covers notches, drilled holes,fissures and material deficits, in particular on the inner side of thehousing wall, which do not penetrate as far as the outer surface of thehousing wall.

[0029] By contrast with this, for the purposes of the invention,apertures are understood as meaning material deficits which reach fromthe inner surface to the outer surface of the housing wall, for examplewindows or drilled holes.

[0030] The recess preferably takes place only in the areas in whichlight-emitting elements are located and preferably in the form that thelight-emitting elements can be introduced or fitted into the recess.

[0031] Circular recesses in the form of a drilled hole have proven to befavorable when using LEDs as light-emitting elements. The diameter ofthe drilled holes is usually slightly larger than the diameter of thelight-emitting element and normally lies in the range from 2 to 6 mm,preferably 3 to 5 mm.

[0032] In principle, the distance of the light-emitting elements fromthe inner surface of the housing wall in the recess is arbitrary, but asmall distance is to be preferred. The perception of the light-emittingelements in the emitting state through the housing wall can be localizedparticularly well if the distance of the light-emitting element from theinner surface of the housing wall in the recess lies in the range from0.5 to 2 mm, preferably in the range from 0.7 to 1 mm.

[0033] The device according to the invention has no recesses, clearancesand/or apertures on the outer surface, at least in the area of thedisplay unit. This ensures a uniformly smooth surface, which can beeasily cleaned.

[0034] Suitable materials for a housing of the device according to theinvention comprise plastics in particular, such as polystyrene (PS),polycarbonate (PC), acrylonitrile-butadiene-styrene (ABS), polybutyleneterephthalate (PBTP), styrene acrylonitrile (SAN), polyamide (PA),polyoxymethylene (POM), polyphenylene oxide (PPO), PE, PP, PTFE andhomopolymers and copolymers of these plastics. The plastics may also beused in a filled or fiber-reinforced form.

[0035] Depending on the application area, the plastics may also besurface-coated, for example with paints, varnishes or lacquers.

[0036] The use of color plastics, for example colored with pigments, isalso possible.

[0037] To ensure the optical perceptibility of the light-emittingelements through color materials, either the light power of thelight-emitting elements must be increased or the wall thickness of thehousing wall must be reduced, at least in the area of the display unit.

[0038] The production process for the housing of the device according tothe invention is based on the materials used.

[0039] The housing of the device according to the invention ispreferably produced by injection molding. However, production bymachining, such as by milling from a shaped body, is also conceivableand possible.

[0040] The devices according to the invention can be used in all sectorsin which a uniform, in particular easy to clean, surface is desirable.

[0041] The devices according to the invention are preferably used in themedical sector. In this sector, it is often of eminent importance thatthe devices can be easily and effectively cleaned, if appropriatedisinfected.

[0042] The following may be mentioned as examples of such devices:exposing devices, mixing devices, in particular devices which are usedin the dental sector.

[0043] The device may also be used to detect the presence, absence oridentification of an item which is at a comparatively close distance inthe area of the housing wall having the recess.

[0044] For this purpose, the housing wall of the device has, preferablymore or less alongside the first recess, a further recess, in which anelement suitable for the detection of electromagnetic radiation islocated. Furthermore, the item is preferably to be formed on its outersurface in such a way that it is able to reflect in a suitable way thelight radiated by the light-emitting element through the housing wall.

[0045] According to experience, the detection of the presence or absenceof the item works all the better the closer the item is to the housingwall of the device. A usable distance lies in the range from 0.01 to 3cm, preferably from 0.5 to 10 mm.

[0046] For its part, the item does not otherwise have to be individuallyidentified any more specifically.

[0047] Suitable elements are, in particular, reflecting surfaces,specularly reflecting materials or else diffusely scattering materials.

[0048] The problem of determining the presence or absence of items oridentifying their nature is known in principle. In this respect,reference is made to WO00/38841 or EP 0 699 582 A1. As a difference fromthe solutions proposed there, the present invention is distinguished bythe fact that the detection system is of a comparatively simpleconstruction and, as a result of the arrangement of the electricalcomponents behind a housing wall which has no apertures, at least inthis area, is very easy to clean, should this be necessary.

[0049] In one particular embodiment, the device is a mixing device, inparticular for mixing dental impression compounds, such as thatdescribed for example in EP 0 492 413 B1. The items to be detected arein this case preferably containers or cartridges to be placed in themixing device, as are described for example in EP 0787655 A2.

[0050] As soon as a cartridge has been placed in the mixing device, thetype of container and the compound with which it is filled can bedetermined by the mixing device in a simple way and the mixing devicecan be controlled according to the container placed in.

[0051] In this way it is also possible to prevent unsuitable containers,which could lead to the mixing device being damaged during itsoperation, from being placed in the mixing device.

[0052] The device specified above, in particular in the form of a mixingdevice, consequently has, in the area of the receptacle for thecontainers to be placed in, a transmitter and a receiver, which arerespectively located in recesses of the housing wall. The light emittedby the transmitter is reflected to a greater or lesser degree by thecontainer to be placed in, according to the nature of the surface of thecontainer. The reflected light is detected by the receiver and generatesa signal there. In the simplest case, the container to be detected hason the surface a light/dark shadowing, for example in the form of abarcode, which can be applied in a simple way by means of an inkjetprinter during the production of the container or parts thereof.

[0053] By providing, if appropriate, a number of transmitters and/or anumber of receivers, it is possible in this way not only to detect thepresence or absence of the container but also to transmit additionalinformation on the container or the compound located in it.

[0054] The embodiment described is consequently distinguished by aseries of advantages, such as simple construction of the detectionsystem comprising a transmitting and reading unit using low-costcomponents, inexpensive application of a coding to a container andeasier cleaning of the transmitting and reading unit in the event ofsoiling, since the device has no apertures, at least in this area.

[0055] Preferred exemplary embodiments are explained below withreference to the drawings.

[0056]FIG. 1 shows a detail of one possible embodiment of the device incross section.

[0057]FIG. 2 shows a specific embodiment for a housing with a partiallytransparent housing.

[0058] The device according to the invention as shown in FIG. 1comprises a light-emitting element (1), for example an LED, and ahousing wall (2), which has in the area (3) in which the light-emittingelement is arranged a recess on the inner side. The light-emittingelement is in the present case partly let into the recess.

[0059] In FIG. 2, opposite the light-emitting element (1) there is anitem (4), with for example a reflecting surface area (5), which reflectsthe light radiated by the light-emitting element (1) through the housingwall (2) and reflects it onto the housing wall (2). There, it can bedetected by an element (6) suitable for optical perception, for examplea photocell, photodiode or a phototransistor, which has been let into arecess. In this way, the device is suitable for registering the presenceor absence of an item which is located at comparatively close range infront of the housing wall.

1. A device, comprising a housing with a housing wall made of anon-transparent plastic, with an outer surface and an inner surface, andan operating-state display unit with at least one light-emittingelement, which is located inside the housing, beneath the inner surfaceof the housing wall, the housing wall having at least one recess in thearea of the light-emitting element and the light intensity of the atleast one light-emitting element being adjusted in such a way that, inthe emitting state, the at least one light-emitting element is opticallyperceptible in a localizable manner through the housing wall only inthis area of the recess.
 2. The device as claimed in claim 1, thehousing wall thickness being less in the area of the recess by at least50% in comparison with the remaining average housing wall thickness. 3.The device as claimed in one of the preceding claims, thenon-transparent plastic being disinfectable.
 4. The device as claimed inone of the preceding claims, the non-transparent plastic being chosenfrom polystyrene (PS), polycarbonate (PC),acrylonitrile-butadiene-styrene (ABS), polybutylene terephthalate(PBTP), styrene acrylonitrile (SAN), polyamide (PA), polyoxymethylene(POM), polyphenylene oxide (PPO), PE, PP, PTFE and homopolymers andcopolymers of these plastics, or comprises such plastics.
 5. The deviceas claimed in one of the preceding claims, the at least onelight-emitting element being let into the at least one recess.
 6. Thedevice as claimed in one of the preceding claims, the housing having noapertures in the area of the display unit.
 7. The device as claimed inone of the preceding claims, the housing wall having at least onefurther recess, into which a detector is let, which makes it possible todetect the light by the light-emitting element through the housing wallonto an item and the light reflected by the latter through the housingwall.
 8. The device as claimed in one of the preceding claims, thedevice being chosen from a medical device, a mixing device or a chargingdevice.
 9. Use of the device as claimed in either of claims 7 and 8 fordetermining the presence, absence or nature of items.
 10. Use of itemsin conjunction with a device as claimed in either of claims 7 and 8, itbeing possible for the presence, absence or nature of the items to bedetermined by the device.